Pipe joint assembly

Abstract: A coupling assembly includes a receiving tubular member (13) defining an opening (27) for receiving a first tubular member (12). The receiving tubular member has an inner portion defining an inner bore dimensioned to receive one end (68) of the first member, and an outer portion defining an internal annular cavity (22) intersecting the inner bore and projecting radially outwardly therefrom. The annular cavity (22) comprises an annular tapered wall portion (25) tapered radially inwardly and projecting longitudinally toward the opening (27), and a split lock ring (72) formed from spring material and disposed in the annular cavity between the first tubular member (12) and the receiving tubular member (13). The lock ring (72) has an outer circumferential surface portion adapted to engage the tapered wall portion (25), and an inner circumferential surface portion (73) adapted to engage an external wall portion of the first tubular member (12). The lock ring (72) is adapted to expand circumferentially into the annular cavity (22) during insertion of said first tubular member into the receiving tubular member, and to be compressed between the tapered wall portion and the external wall portion in response to relative longitudinal separating movement between the first tubular member and the receiving tubular member. The inner circumferential surface portion (73) of the lock ring defines first and second substantially parallel, spaced apart, circumferentially extending knife edges (76, 81). Also included is an annular sealing member (36) disposed in the annular cavity between the lock ring and the inner bore, the sealing member being dimensioned to be engaged between the first tubular member and the receiving tubular member. Under high pressure conditions both of the knife edges (76, 81) penetrate the external wall portion so as to prevent longitudinal movement of the first tubular member relative to the receiving tubular member.

Description: The invention relates generally to an improved pipe coupling assembly and, more particularly, to an easily assembled and disassembled pipe coupling assembly. Known methods for connecting a length of metal pipe or tubing to valves or pipe fittings such as elbows and tees include the use of threaded connectors, soldering, compression fitting, flaring and welding. Non-metallic pipe, such as thermoplastic pipe, may also be joined by adhesives. These methods are all subject to various drawbacks. Methods calling for the application of heat or force can be awkward and time consuming to practice in cramped and inaccessible areas, for example, areas in which residential plumbing is typically located. Soldering, welding and the like require the attention of a skilled worker using special tools to produce a good connection. Moreover, it is often difficult and time consuming to disconnect a length of pipe from a fitting once they have been joined, and it is often not possible to disassemble the joint without damaging the pipe or the fitting to such an extent that they cannot later be rejoined. Acceptable pipe joints are more difficult to make when the pipe is to carry a fluid under pressure. Even where threaded pipe and threaded connectors are used, greater skill is required to produce a strong and leakproof seal which will withstand the pressure rating of the pipe being joined. For proper sealing under pressure, washers or O-rings are often included in the joint. If the washer and pipe are made of dissimilar metals, they will sometimes undergo electrolysis in the presence of moisture in the joint or water and chemical agents flowing through the pipe. Electrolytic action leads to degradation of the washer, which can eventually cause the joint to leak and loosen the locking action of lock washers. Some of the aforementioned drawbacks are overcome by the use of plastic pipe joined by adhesive. But plastic pipe is difficult to connect directly to metal valve fittings without special adaptors. Moreover, once sealed with adhesive, prior plastic pipe joints cannot be readily undone. Disclosed in our EP-A-0 588 596, published on 23.03.1994, (US Appln. No. 07/944,373) is an improved coupling assembly that is illustrated in Figs. 1-9 of the accompanying drawings. A pipe coupling assembly 11 includes an inner first tubular member 12 and an outer receiving tubular member 13. The tubular member 12 generally will be a length of pipe or tubing such as commonly employed for the delivery of fluids. The embracing tubular member 13 will generally form a part of a pipe fitting, such as an elbow, tee, or the like, or will form a part of some other component of a piping system, such as a valve. The receiving tubular member 13 includes an inner portion 14, an outer portion 15 and an end portion 16 with a radially inwardly directed rim 18 that defines a circular opening 17 and an inwardly directed shoulder 19. Defined by the inner portion 14 of the receiving tubular member 13 is an inner bore 21 dimensioned to snugly receive the outer surface of the first tubular member 12. The outer portion 15 of the receiving tubular member 13 defines an annular cavity 22 intercepting the inner bore 21 and projecting radially outwardly therefrom. Forming the annular cavity 22 is a cylindrical wall portion 24 and an annular tapered wall portion 25 joining the cylindrical wall portion 24 and the shoulder 19 surrounding the opening 17. An annular gap 27 is formed between the first tubular member 12 and the rim 17 which has a diameter larger than the outer surface of the member 12. Defining an annular shoulder 28 on the receiving tubular member 13 is a counterbore 29. An annular rib 31 on the receiving tubular member 13 projects inwardly from the cylindrical portion 24 and separates the cavity 22 into longitudinally separated cavity portions 32 and 33. Projecting inwardly from the cylindrical wall portion 24 in the cavity portion 32 is a longitudinally disposed ridge 34. The pipe coupling assembly 11 also includes a split lock ring 35 disposed in the cavity portion 32, a sealing member 36 such as a resilient O-ring disposed in the cavity portion 33, and a split auxiliary ring 37 disposed in the cavity portion between the lock ring 35 and the annular rib 31. The lock ring 35 is made from a material suitable to establish a good spring characteristic. As shown in Figs. 3-5, the lock ring 35 has a circular cross-section, an outer circumferential surface portion 41 of diameter D less than the diameter of the adjacent cylindrical wall portion 24, and an inner circumferential surface portion 42 of diameter d less than the outer diameter of the first tubular member 12. Cut in the inner surface portion 42 is a circumferential groove 44 formed by one wall 43 oriented perpendicular to an outer surface 45 of the first tubular member 12, and another wall 47 extending between the outer surface of the ring 35 and the one wall 43 and oriented perpendicular thereto. The another wall 47 extends from the one wall 43 away from the opening 17 in the tubular member 13. Formed by the periphery of the one wall 43 is a circumferential knife edge 48 extending parallel to the outer surface 45 of the first tubular member 12. First and second ends 51, 52 of the lock ring 35 straddle a split therein and, as shown in Fig. 3, the second end 52 is axially displaced from the first end 51 which is circumferentially aligned with the major portion of the ring 35. During assembly of the coupling assembly 11, the first tubular member 12 is inserted through the opening 17 in the receiving tubular member 13,until an inner end 68 of the member 12 engages the annular shoulder 28,as shown in Figs.8 and 9. As the first tubular member 12 moves through the annular cavity 22, its external surface engages the knife edge inner surface 48 of the lock ring 35 expanding it outwardly into the cavity portion 32 of the annular cavity 22. However, since the outer diameter D of the lock ring 35 is less than that of the cylindrical wall portion 24, inward axial movement of the first tubular member 12 is not restricted. In addition, the auxiliary ring 37 is compressed between the cylindrical surface portion 24 and the outer surface of the first tubular member 12 which outer surface is scored by longitudinal projecting edges 64 of circumferentially spaced teeth 63 around the inner circumference of the auxiliary ring 37. Because of this penetration of the first tubular member 12 by the edges 64 on the compressed auxiliary ring 37, rotation of the first member 12 within the receiving member 13 is prevented. A tapered annular transitional surface 69 between the cylindrical surface portion 24 and the inner bore 21 accommodates longitudinal migration of the sealing member 36 so as to prevent damage thereto during insertion of the first tubular member 12 as shown in Fig. 8. After full insertion, the first tubular member 12 is partially withdrawn to produce a longitudinal separation movement relative to the receiving tubular member 13. During that movement, the lock ring 35 is forced longitudinally outwardly in the annular cavity 22 and tightly compressed therein between the shoulder stop 19, the tapered wall portion 25 and the outer surface of the first tubular member 12 as shown in Fig. 9. Because of the penetration of the outer surface of the first tubular member 12 by the knife edge 48 on the lock ring 35, further relative longitudinal movement between the member 12 and the receiving tubular member 13 is prevented. In addition, the second end 52 of the lock ring 35 is forced into circumferential alignment with the first end 51 creating an axially directed force that biases the member 12 inwardly in the member 13. Fluid pressure within the coupling 11 exerts on the first member 12 a longitudinally outwardly directed force F that is transferred by the tapered wall portion 25 radially inwardly on the lock ring 35. Consequently, the knife edge 48 is driven further into the outer surface of the first member 12, enhancing the securement thereof to the receiving member 13. With the parts in the relative positions shown in Fig. 9, the O-ring 36 is engaged between the cylindrical surface portion 24 and the outer surface of the first tubular member 12 to create n fluid tight seal therebetween. The annular rib 31 prevents damage of the annular sealing member 36 by the teeth 63 on the auxiliary ring 37. The coupling assembly 11 alleviates many of the above noted problems. However, the operational characteristics of the coupling 11 are not suitable for all applications. The present invention relates to a coupling assembly generally of the type disclosed in our EP-A-0588596 , and also generally of the type disclosed in GB-A-2,166,508 and defined in the precharcterising clause of claim 1 . The object of this invention is to provide an improved high pressure pipe coupling assembly that can be easily assembled and disassembled by unskilled workers. According to the present invention, there is provided a coupling assembly as defined in the characterising clause of claim 1 . The lock ring may have first and second ends normally axially displaced, the first and second ends being forced into substantial alignment in response to compression of the lock ring between the tapered wall portion and the external wall portion. With its ends aligned, the lock ring creates a force biasing the first tubular member into the receiving tubular member. The split ring may have an inner diameter less than the outer diameter of the fist tubular member. This feature assures penetration of the first tubular member by the knife edge means. The receiving tubular member may be plastic, and the inner bore therein may terminate with an annular groove facing the opening, partially formed by the inner bore, and dimensioned to receive the inner end of the first tubular member. Preferably, the first tubular member comprises radially spaced apart plastic laminations separated by a metal lamination. The plastic laminations become swedged into the groove to form a seal around the metal lamination. Reference will now be made to the accompanying drawings, wherein: Figs. 1 - 9 illustrate our prior coupling assembly; Fig. 10 is a partial longitudinal cross sectional view of a coupling assembly embodying the invention, shown partially assembled; and Fig. 11 is a cross sectional view of the assembly of Fig. 10 shown fully assembled. The coupling assembly 85 shown in Figs. 10 and 11 is similar in certain respects to the prior coupling assembly 11 shown in Figs. 1-9 , and identical parts of the two assemblies have been given the same reference numerals. Eliminated from the coupling assembly 85 is the auxiliary ring 37 used in the prior coupling assembly 11 . The coupling assembly 85 includes an inner first tubular member 86 , and a first tubular member-receiving arrangement including an outer receiving plastic tubular member 87 and an outer tubular coupling member 88 . The receiving tubular member 87 includes an inner portion 89 and an outer portion 91 and an externally threaded outer surface 92 . Defined by the inner portion 89 is an inner bore 93 dimensioned to snugly receive the outer surface of the first tubular tubular member 86 . Also defined by the inner portion 89 of the receiving tubular member 87 is an annular groove 95 partially formed by the inner bore 93 and facing an opening 96 for receiving the first tubular member 86. The annular groove 95 has a.radially inwardly and longitudinally outwardly tapered surface 97. Defined by the outer portion 91 of the receiving tubular member 87 is an radially outwardly opening annular cavity 99 that intersects the inner bore 93. The tubular coupling member 88 has an internally threaded portion 101 for engaging the externally threaded portion 92 of the receiving member 87. Formed at one end of the coupling member 88 is an annular reentrant portion 102 that is dimensioned to enter the annular cavity 99 in the receiving member 88. The reentrant portion 102 has a inwardly tapered wall portion 105 projecting radially inwardly and toward the opening 96. Preferably, the first tubular member 86 is composed of an outer plastic lamination 107, an inner plastic lamination 108, and an intermediate metal lamination 109 between the inner and outer plastic laminations 107, 108. Straddled by a plastic spacer ring 111 in the annular cavity 99 is an internal O-ring 112 and a split lock ring 113 that is substantially identical to the split lock ring 35 described above and shown in Figs. 3 and 4 made from a material suitable to establish good spring characteristics. Again, the ring 113 is a split ring and dimensioned for operation in the same manner as described above for the split ring 35. During assembly of the coupling assembly 85 the first tubular member is inserted through the opening 96 in the receiving tubular member 87 and into engagement with the tapered surface 97 of the annular groove 95 as shown in Fig. 15. Next,the coupling member 88 is rotated inwardly on the receiving member 87 to produce movement of the reentrant portion 102 into the annular cavity 99. Engagement between the tapered surface 105 and the split ring 113 causes penetration of the outer lamination 107 of the first tubular member 86 by a knife edge 115 on the split ring 113. Because of the engagement between the ring 113 and the first outer lamination 107, further inward movement of the reentrant portion 102 forces an inner end 121 of the first tubular member 86 into the annular groove 95 in the receiving member 87. That action swedges the inner end 121 of the first tubular member 86 against the tapered surface 97 and produces between the engaging plastic surfaces of the annular groove 95 and the inner lamination 108 a high force creating a fluid tight seal. That seal prevents contact between a fluid within the tubular member 86 and the metal lamination 109 to insure against corrosion thereof. In addition, the inward movement of the reentrant portion 102 forces the spacer ring 111 inwardly compressing the O-ring 112 to create a secondary seal between the O-ring 112 and the fixed outer lamination 107 in the event of the leakage through the seal between the inner lamination 108 and the annular groove 95 of the receiving tubular member 87.

Claims: A coupling assembly which connects one end ( 121 ) of a first tubular member ( 86 ) to a component of a piping system, said assembly comprising: a receiving arrangement on said component and defining an opening ( 96 ) adapted to receive said first tubular member, said receiving arrangement including a receiving tubular member ( 87 ) having an inner portion ( 89 ) defining an inner bore ( 93 ) dimensioned to receive said one end ( 121 ), and an outer portion ( 91 ) defining an internal annular cavity ( 99 ) intersecting said inner bore and projecting radially outwardly therefrom, said receiving arrangement further including an annular tapered surface ( 105 ) associated with said annular cavity, tapered radially inwardly and projecting longitudinally toward said opening ( 96 ); a split lock ring ( 113 ) formed from spring material and disposed in said annular cavity ( 99 ) between said receiving tubular member ( 87 ) and said first tubular member ( 86 ) when received in said receiving arrangement, said lock ring ( 113 ) having an outer circumferential surface portion adapted to engage said tapered surface ( 105 ) and an inner circumferential surface portion adapted to engage an external wall portion ( 107 ) of said first tubular member ( 86 ), said lock ring ( 113 ) being adapted to expand circumferentially into said annular cavity ( 99 ) during insertion of said first tubular member ( 86 ) into said receiving arrangement and to be compressed between said tapered surface ( 105 ) and said external wall portion ( 107 ) in response to relative longitudinal separating movement between said first tubular member ( 86 ) and said receiving arrangement, and said inner circumferential surface portion defining at least one circumferentially extending knife edge means ( 115 ) for penetrating said external wall portion ( 107 ) so as to prevent longitudinal movement of said first tubular member ( 86 ) relative to said receiving arrangement; and an annular sealing member ( 112 ) disposed in said annular cavity between said lock ring ( 113 ) and said inner bore ( 93 ), said sealing member being dimensioned to be engaged between said first tubular member ( 86 ) and said receiving tubular member ( 87 ); characterised in that : said receiving tubular member ( 87 ) has an externally threaded portion ( 92 ); said receiving arrangement further includes an outer tubular coupling member ( 88 ) having an internally threaded portion ( 101 ) for engaging the threaded portion ( 92 ) of said receiving member, and an annular reentrant portion ( 102 ) received by said annular cavity ( 99 ) and defining said inwardly tapered surface ( 105 ) which projects inwardly into the annular cavity and traps said lock ring ( 113 ) between said tapered surface ( 105 ) and said external wall portion ( 107 ) of said first tubular member when said coupling member and receiving member are threadedly engaged; and said receiving tubular member ( 87 ) further comprises an annular groove ( 95 ) bounded by said inner bore ( 93 ) and an annular tapered wall surface ( 97 ) tapered radially inwardly and projecting outwardly towards said opening, wherein, when said first tubular member ( 86 ) is received in said receiving arrangement and said outer tubular coupling member ( 88 ) engages said lock ring ( 113 ), said one end ( 121 ) of said first tubular member ( 86 ) swedges against said annular tapered wall surface ( 97 ) of said annular groove ( 95 ) to form a fluid tight seal therebetween.

Inventors: GRENIER WILFRED J, GRENIER, WILFRED J.
Applicants: ROVAC CORP, ROVAC CORPORATION
Application year: 1994
Main classification: F16L19
IPC codes: F16L37, F16L19, F16L21